Mod your Beresford 7520

[leo]

Are we back on track now?

I've spent my pocket money this month on AMB's γ1 (Gamma 1) portable DAC kit (awaiting parts as we speak) - So here's a couple of suggestions for you guys to try:

The AD8620 - I know it's a FET input op-amp, but I have used it in the past and found it difficult to beat if you prefer a more forward sound. Quite expensive at the moment though and only available in SOIC. But these guys do a pre-mounted chip: http://cimarrontechnology.com/pre-mo...0-970601s.aspx and their shipping is very reasonable.

The AD826 - I have never used this op-amp, but it gets good reviews on the forums. May be a bit of a handfull to control like the THS4032, but the spec sheet is very impressive. Price is reasonable at about 5GBP, but it does come in 8pin DIP.


OK, I am looking to Stan or Leo for their advice next - I have been pondering whether it would be worthwhile upgrading the electrolytic capacitors on the HA board of the TC-7520 to something like Rubycon ZA or Nichicon "MUSE". Is it worth the effort? What are the likely sonic gains, if any? Your help will be appreciated.


Ken

AD826, not sure if this one will behave in the 7520, if it does it should be very good.

AD8620 has its fans, its similar to AD8066 but behaves more in a wider range of circuits, some find it lacks bottom end
Last time I used one of these adding a CRD from output to supply pin with worse PSRR greatly improved it

I've tried dozens of op-amps, not in this dac though

[jon1]

Jon,

Sorry to hear about the ebay dac, maybe best to start another thread discussing this one but you sure its just the SA7220 which is at fault? Did you try bypassing it? If the rest of the doc is ok you should be able to run it in NOS until you get a replacement SAA7220

Leo... the bypass is already in had just in case...will start a new thread when we get some life in the dac....



jon

[Covenant]

At some point I want to use my 7520 as a power amp, this being a route that Stan designed it for. I imagine that the volume pot must be good quality but was wondering if there is room for something more exotic like a stepped attenuator.
Any thoughts?

[leo]

At some point I want to use my 7520 as a power amp, this being a route that Stan designed it for. I imagine that the volume pot must be good quality but was wondering if there is room for something more exotic like a stepped attenuator.
Any thoughts?

Stepped attenuators are quite big, what sort of pot is fitted in a 7520? is it something like a mini pot or standard sized job?

A digital attenuator would be far more interesting imo

[leo]

For the cheap steppers theres some on here http://stores.shop.ebay.co.uk/Vintag...__W0QQ_armrsZ1 and for the more pricey http://www.dact.com/html/attenuators.html

Dimensions etc should be easy to find

[Covenant]

Stepped attenuators are quite big, what sort of pot is fitted in a 7520? is it something like a mini pot or standard sized job?

A digital attenuator would be far more interesting imo

Surprised you said that Leo. I thought digital attenuators were not considered as good as something with Vishay or Dale resistors in it.

[leo]

Surprised you said that Leo. I thought digital attenuators were not considered as good as something with Vishay or Dale resistors in it.

For a separate pre/line stage I probably would go with a stepped attenuator like the Dact but for something like a small dac a digital one maybe more convenient, more compact etc
Also be easier to add remote if really required

[Dougr33]

One reason I like sitting next to my 7520 "pre amp" is that I can adjust the volume in very fine increments. Having had the Arcam A85 integrated (digital volume +dig. balance and tone from remote!) and two NAD integrated, the problem with the remotes was getting fine adjustments with each push of the button. No problem now. Plus I like being able to switch back and forth between the coax and usb inputs.

[Covenant]

I prefer to get up and adjust the volume as its about the only exercise I get.

[Dougr33]

That would explain my recent weight gain!